On the measurement of hardness of super-hard coatings

A precise correcting method for the study of the superhard material using nanoindentation tests

“…To include the effect of the elastic deformation of the indenter, in the method of Oliver and Pharr, 2 the reduced modulus is applied; however, controversy arose recently for this common practice. [21][22][23][24] The present work is a further investigation on an elastic indenter indenting into an elastic half-space that aims to reconcile some apparent inconsistencies found in the literature and provides a more accurate method in extracting mechanical properties for superhard materials using a conical indenter of 70.3°. In summary, the following contributions have been made.…”

“…A conical diamond indenter of 70.3°indenting into an elastic perfectly plastic superhard material with the Poisson's ratio ‫ס‬ 0.0, the Young's modulus E ‫ס‬ 800 GPa, and the yield strength y ‫ס‬ 20 GPa is analyzed. Fitting the upper 80% of the unloading curve 24 using the power function, 2 the initial unloading slope S is determined. Using S, the maximum indentation load P m , and the maximum indentation depth h m as inputs, the Young's modulus is determined from the following procedure.…”

“…(15) and that directly obtained from the finite element simulation is 3.7%. In a recent article, Fischer-Cripps et al 24 performed an interesting experiment by indenting a diamond indenter into an industrial diamond substrate. Using the method of Oliver and Pharr, 2 they obtained a quite reasonable result for the Young's modulus of the diamond substrate.…”

“…In the work of Fischer-Cripps et al, 24 a correction factor of 1.034 was used in Eq. (14), which is from King.…”

“…To include the effect of the indenter compliance, a common practice of so-called reduced modulus was used in the method of Oliver and Pharr. 2 There have recently been a few conflicting reports [21][22][23][24] regarding the applicability of the reduced modulus, as described in detail below in this section.…”